| Diagnosis and Testing Principles of Operations The Door Switch Lock Function When a door lock switch is moved into the lock position or a door lock cylinder is rotated to the lock position, the door lock switch grounds the lock circuit input to the central security module (CSM). The CSM then provides 12 volts to one side of the door lock actuators contained in the door latch unit and simultaneously grounds the other side of the door lock actuators. This completes the door lock actuator circuit, causing the door lock actuators to rotate a cam assembly, which then locks the doors. The Door Switch Unlock Function When a door lock switch is moved into the unlock position, the door lock switch grounds the unlock circuit input to the CSM. The CSM then provides 12 volts to the opposite side (relative to locking the door) of the door lock actuator(s) contained in the door latch unit and simultaneously grounds the other side of the door lock actuator(s). This completes the door lock actuator circuit, causing the door lock actuator(s) to rotate a cam assembly in the opposite direction, which then unlocks the door(s). The 12 volts which the CSM provides to the door lock actuator(s) are provided to each door lock actuator from the individual pins on the CSM connector. The Liftgate Release When the liftgate release switch is depressed, it grounds an input circuit to the CSM. When the CSM senses the ground, it sends 12 volts to cycle the liftgate release actuator. Door Lock Cylinder Functions Both the driver and passenger doors can be locked from either door lock cylinder. When the ignition key is inserted into either door lock and is rotated into the lock position, the linkage moves to rotate a cam in the door latch unit. When the cam in the door latch rotates, it mechanically moves the door latch (in the door in which the key is being used) into the locked position. The other doors are locked electronically. Keyless Entry When a remote transmitter button is depressed, it transmits the appropriate command to the CSM as a radio frequency. The CSM receives the command from the remote transmitter through an antenna, which is incorporated in the CSM. When the CSM receives a command from the remote transmitter, it then sends the appropriate output to control the desired devices. These outputs devices include: - The front and rear door lock units.
- CTM.
- The liftgate release motor.
- The right and left side turn signal lamp(s).
The CSM sends a signal to the CTM when courtesy lamp illumination is required. Inspection and Verification -
NOTE:Make sure that the battery is fully charged before starting electrical diagnosis. NOTE:Prior to carrying out the CSM Self - Test, make sure that the doors are open. Verify the customer concern by operating the system. - Visually inspect for obvious signs of mechanical and electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Binding lock/latch mechanisms
- Binding linkage
- Misaligned door
| - Vehicle battery
- Remote transmitter batteries
- Remote transmitter
- Unprogrammed remote transmitter
- Central junction box (CJB) fuse 63 (20A)
- Wiring harness
- Loose or corroded connector(s)
- Circuit(s)
- Door lock switch
- Power door lock actuator
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If concern is not visually evident, verify the symptom and refer to WDS to diagnose the system.
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